Terminal construction for electrical apparatus



Dec. 8, 1953 TERMINAL R. P. BALLOU 2,662,221

CONSTRUCTION FOR ELECTRICAL APPARATUS Filed Aug. 30, 1949 INVENTOR. fi/CHARD BAL4OU arrow/5x5 MM BY I r I Patented Dec. 8, 1953 TERMINAL CONSTRUCTION FOR ELEC- TRICAIJ APPARATUS Richard P. Ballou, Hartford, Conn., assignor to Federal Electric Products Company, Newark,

N. J., a corporation Application August 30, 1949, Serial No. 113,157

7 Claims.

This invention relates, in general, to an improved terminal construction for connecting components or conducting parts in electrical equipment, and more particularly, to such a terminal especially adapted for use in an automatic circuit breaker of the general type disclosed in the patent to Joseph Sachs, No. 2,185,525, dated January 2, 1940, and used as a motor starter.

An essential component in an electrical device, such as, for example, the thermostat heater in the above identified circuit breaker, can be bypassed by connecting a wire or jumper across the terminals of the device to which the component is connected. It is apparent that this may result in damage to equipment connected to the device due. for example, to excess current flow through the wire. Therefore, it is an object of this invention to provide a mounting terminal so constructed as to serve notice that it is undesirable to connect any component thereto except a component having a construction complementary thereto.

Another object is to provide a terminal to which an ordinary piece of wire or a jumper cannot be readily secured, but to which the intended part, for example, the heater, can be readily secured, without requiring special tools or effort, to provide proper mechanical alignment and to achieve a good electrical connection.

A further object is to simplify the mechanical aspects of such a mounting terminal by reducing the number of mounting parts to only a single insert which, in addition to electrically and mechanically connecting two or more parts together, will also mechanically connect said parts to the device with which they are associated.

The above and other objects, features and advantages of the invention will be fully understood from the following description, considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a front view of a manual motor starter, embodying the invention, the thermal overload relays being located on each side of the handle, the relay heater being omitted on the left hand side and shown on the right hand side;

Fig. 2 is a side view of the device illustrated in Fig. 1, parts thereof being omitted;

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 1;

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 1; and

Fig. 5 shows a conducting strap embodying the invention.

Referring to Fig. 1, there is illustrated a manual motor starter or circuit breaker H), of the general type disclosed in the above identified patcut, comprising the metallic mounting plate i2 to which is secured the contact block 14 provided with stationary contacts l6 and I3, and the relay block 26, the carriage 22 being provided with companion movable contacts 24 and 26 reciprocable between said blocks, which, together with said carriage, are formed of suitable insulation material. The line terminals 28 are secured to block [4 by screws 30 and are each connected to a companion stationary contact l8 and are provided with a terminal screw 32 for connection to the current-carrying line (not illustrated). Each of said stationary contacts I8 is connected to a companion stationary contact 16 by a companion bridging contact member 34, which is mounted on carriage 22 and carries movable contacts 24 and 26 for engagement with stationary contacts I6 and 18, respectively, substantially as shown in said Patent No. 2,185,525 or in application, Serial No. 38,686, filed July 14, 1948, by myself and Daniel F. Daly, as joint inventors, and assigned to the assignee of the present application, and issued as Pat. No. 2,546,663 on March 27, 1951. Stationary contact 16 is connected to circuit-breaker terminal 36 which is secured to block M by screw 38 and is provided with the terminal connecting screw 40. A conducting strap 42 is connected between terminal 36 and a heater terminal 44 in relay block 20, heater 46 being secured between said terminal 44 and the load terminal 48 which is secured to relay block 26 by screw 50 and is provided with terminal screw 52 for connection to a load (not shown). Heater 46 is positioned in juxtaposition to an electro-responsive device 54, preferably a thermostatic bi-metallic strip substantially as shown in said Patent 2,185,525, said device being automatically responsive to a predetermined current condition in heater 46 to break the circuit btween the line and the load, substantially as described in said patent. The mechanism for actuating carriage 20 is generally indicated at 5B and may be the same as in the above mentioned Patent 2,185,525, it being understood, however, that the actuating mechanism may be of the mechanical or electrical type, as is Well known to those skilled in the art. As the operation of a thermal overload relay is well known to those skilled in the art, and since the relay, per se, does not constitute part of the present invention, further description thereof is deemed unnecessary.

The present invention is embodied in the connecting terminal 44 and the parts connected thereto, at which terminal the metal conducting strap 42 which is connected to switch terminal 36, makes contact with the heater element 46. To constitute the connecting terminal 44, insulating block 26, when molded, is provided with a surface seat or recess 58 (Fig. 4) which exte d below the adjacent surface portions 60, said recess having an irregular conformation provided r, by the saw tooth portions or angular protuberances 62 (Fig. 1) which project from the opposing lateral walls 64 thereof, the bottom wall 56 of the recess being apertured at 61 and opening into a preferably internally threaded metal insert or sleeve 68 molded into block 20 (Fig. 4). It will be apparent that due to the irregular conformation of recess 58, it will require considerable manipulation, with no parts in terminal M, to tighten an ordinary screw or washer on the insert, even with a wire under the screw, since the diameter of the screw head or washer, which would normally be used with insert 68, would be too large to enter the recess due to portions 62, and a screw head or washer small enough to fit between said portions would normally be of in- .sufiicient diameter to retain a wire thereunder. Tharefore, the irregular conformation will indicate that it is intended that only a part having a cqmplementary conformation should be connected to the terminal. 7 7 I a o The parts to beconnected at terminal 44 are provided with oonformations or contours complemental to that of recess 58. Strap 42 is preferably stamped from sheet material, which is a good electrical conductor, and is provided at one end with an inwardly extending portion 10 which is slightly narrower than the recess and which is provided with notches 12 in the opposing lateral edge -portions thereof, said notches being shaped to cooperate with portions 62 which extend thereinto, thereby permitting the seating of end portion 10 in the recess, said end portion being provided also with an aperture 14 positioned to register with aperture 61 and insert 68, said strap being provided at its opposite end with a standard terminal connecting portion fl provided with aperture 11 to receive terminal screw 40. Similarly, heater 46 has an insnlated end portion 16 which is provided with similar notches I8 in the opposing lateral edges thereof and with an aperture80 in registry with aperture 61 and insert 68,. said aperture 80 being provided with a contact boss 82 of electrically conducting material, said boss being connected to the heater grid 84, as is well known. Heater portion I6 is preferablypositioned in recess 58 to overlie strap portion 10, both of said portions being secured together by a terminal securing screw 86 which projects through apertures 80, 6 1 and [4 to threadedly engage insert 68 to provide for both the mechanical and electrical connection of strap 42 and heater 46, it being noted, in Figs. 2, 3 and 4, that strap portion and heater portion 'I6 are of such thickness that the upper surface of heater portion is flush with or may be above) the upper surface of the adjacent block portions 60 when screw 86 is fully threaded into the insert whereby boss 82 'makes contact with strap portion 10 and the screw head does not enter therecess. To maintain the heater in a horizontal plane, block 20 is provided 'with an additional surface seator recess 88 (Fig. 4), for load terminal 48, in which a conducting "scfews'fl inserted through boss 56 therein.

strap 90 is secured by screw 50, said strap being 'It'will'be understoodthatseatbt need riot be recessed but may extend above the surface of block 2U, bottom 'a11 sis being flush with the ad- 'jac'ent surface portions 60. w r

, From the abovedesoription, it will be apparent that'the terminal connector illustrated and de-. 1

'scribed'hereinis well adapte'd to fulfill the ob- 4 jects herein in providing a recess having an irregular conformation and into which only parts having a cooperating conformation are insertable, said terminal requiring only one insert and all the parts being secured by a single terminal screw threaded into the insert.

While the presently preferred embodiment of my invention has been illustrated and described in connection with a strap and a heater in an automatic circuit breaker, it will be understood that its use is not limited to the strap, the heater, "and/or the circuit breaker, and that the terminal construction herein disclosed is adapted for use wherever an electrical'and/or mechanical connection is to be made between two or more members and regardless of whether or not it is desired to avoid the insertion of a wire or jumper? as above set forth. It 'willalso be understood that the irregular conformation of the terminal recessand the connecting parts is not limited to the conformation illustrated and described.

While I have shown anddescribed the presently preferred embodiment of my invention, it will be understood that various changes in the details of construction and in the form and arrangement of parts 'mry be made without departing from the underlying idea or principles of this invention within the scope of the appended claims, p

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A connection terminal for an electric device comprising a part formed of insulation niaterial and provided with a recess defined in a surface thereof, said recess having a bottom wall and opposing walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, a headed terminal securing member adapted for releasable engagement in said insert, and a wallportion projecting from one of said opposing walls toward the other of said walls, the head of said terminal member beingdim'en'sioned relative to said recess and said wall projection to prevent the head of said terminal member from entering said recess atsaid surface, whereby to prevent the tightening of said securing member in said insert. v J H r a 2. A connection terminal for an electric device comprising a part formed of insulation material and provided with a recess defined in 'a surface thereof, said recess'having a bottoin'wall and opposing walls extendingiupwa'rdly there- :from to said surface, insert means extending from said bottom'wall in a direction away from said surface, and a headed terminal "securing member adapted for releasable engagement in said insert, each of said opposing walls being provided with a wall portion projecting toward the other of said opposing walls, the head of said terminal member being dimensioned relative to said recess and said wall projection to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert. I V v I 3. A connection terminal for an electric device comprising a partformed of insulation material and providedwith a recess defined in a surface thereof, saidrecess having a bottom wall and opposing walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, and a headed terminal securing member adapted for releasable engagement in said insert, each of said opposing walls being provided with a wall portion projecting toward the other of said opposing walls for a distance sufficient to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert, said bottom wall having defined therein an opening which communicates with said insert means for insertion of said terminal member therein, said opening being disposed between the lines of projection of said projecting portions, respectively.

4. In electrical apparatus, a connection terminal comprising a part formed of insulation material and provided with a recess defined in a surface thereof, said recess having a bottom wall and opposing walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, a headed terminal securing member adapted for releasable engagement in said insert, and a wall portion projecting from one of said opposing walls toward the other of said walls for a distance sufiicient to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert, and at least a pair of conducting members each having an apertured portion provided with a conformation complemental to said wall portion whereby said i insulation part for engagement by the head of said terminal member for securely releasably retaining said conducting members in electrical and mechanical engagement in said recess.

5. In electrical apparatus, a connection terminal comprising a part formed of insulation material and provided with a recess defined in a surface thereof, said recess having a bottom wall and opposing Walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, a headed terminal securing member adapted for releasable engagement in said insert, each of said opposing walls being provided with a wall portion projecting toward the other of said opposing walls for a distance sufiicient to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert, and at least a pair of conducting members each having an apertured portion provided with a conformation complemental to said wall portions whereby said conducting members are removably engageable in overlapping disposition in said recess, said terminal member extending through said apertured portions into said insert means, and said conducting members having a combined overlapping dimension such that, with the lowermost conductin member disposed on said bottom wall, the upper surface of the uppermost conducting member will be at least flush with said surface of said insulation part for engagement of the head of said terminal member for securely releasably retaining said conducting members in electrical and mechanical engagement in said recess.

6. In electrical apparatus, a connection terminal comprising a part formed of insulation material and provided with a recess defined in a surface thereof, said recess having a bottom wall and opposing walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, a headed terminal securing member adapted for releasable engagement in said insert, each of said opposing walls being provided with a wall portion projecting toward the other of said opposing walls for a distance sufficient to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert, and at least a pair of conducting members each having an apertured portion provided with a conformation complemental to said wall portions whereby said conducting members are removably engageable in overlapping disposition in said recess, said terminal member extending through said apertured portions into said insert means, and said conducting members having a combined overlapping dimension such that, with the lowermost conducting member disposed on said bottom wall, the upper surface of the uppermost conducting member will be at least flush with said surface of said insulation part for engagement of the head of said terminal member for securely releasably retaining said conducting members in electrical and mechanical engagement in said recess, said bottom wall having defined therein an opening which communicates with said insert means for insertion of said terminal member therein, said opening being disposed between the lines of projection of said projecting portions, respectively.

'7, A connection terminal for in electric device comprising a part formed of insulation material and provided with a recess defined in a surface thereof, said recess having a bottom wall and opposing walls extending upwardly therefrom to said surface, insert means extending from said bottom wall in a direction away from said surface, a headed terminal securing member adapted for releasable engagement in said insert, and a wall portion projecting from one of said opposing walls toward the other of said walls for a distance sufiicient to prevent the head of said terminal member from entering said recess at said surface, whereby to prevent the tightening of said securing member in said insert, said insert means being an internally threaded cylinder formed in said insulation part and the terminal member being a headed screw threadedly engaged in said insert, the head of said screw being dimensioned relative to said recess and said wall projection to prevent the entry of said head into said recess, whereby said screw can not be driven home.

RICHARD P. BALLOU.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,144,781 Ravlin June 29, 1915 1,204,691 Sachs Nov. 14, 1916 1,359,143 Amos Nov. 16, 1920 1,827,565 De Reamer Oct. 13, 1931 1,919,975 Chapman July 25, 1933 2,007,357 Anderson July 9, 1935 2,052,272 Auth Aug. 25, 1936 2,229,211 Korengold Jan. 21, 1941 2,411,014 Warnke Nov. 12, 1946 

